Seat belt apparatus and seat belt retractor

ABSTRACT

A seat belt retractor includes a frame having a back plate and a side wall protruding from each of multiple side edges of the back plate. The seat belt retractor also includes a spool supported by the frame and configured to rotate and wind a seat belt, a motor configured to rotate the spool, and an electronic control unit configured to drive and control the motor. The electronic control unit is mounted between the side walls of the frame and the back plate is disposed in an inner space of a vehicle body member and faces a vehicle interior direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. application Ser. No.12/216,024, filed Jun. 27, 2008, which is incorporated herein byreference in its entirety

BACKGROUND

The present disclosure generally relates to a seat belt apparatus or aseat belt retractor that carries out at least one of retracting andwithdrawing operations for a seat belt by rotating a spool with anelectric motor. More specifically, the disclosure relates to a seat beltapparatus or a seat belt retractor where the electric motor iscontrolled by an electronic control unit (ECU).

A conventional seat belt apparatus mounted on a motor vehicle (e.g., anautomobile) is configured to restrain an occupant with a seat belt so heor she does not leave a seat during an event such as a collision of amotor vehicle, hard braking, etc. The seat belt apparatus includes aseat belt retractor for retracting the seat belt. A conventional seatbelt retractor winds the seat belt on a spool when the seat belt is notworn and also allows the seat belt to be withdrawn and worn by theoccupant. The seat belt retractor typically includes a locking mechanismthat activates during an event to block rotation of the spool in awithdrawing direction so the seat belt cannot be withdrawn and so theoccupant is restrained.

SUMMARY

One embodiment of the disclosure relates to a seat belt retractorincluding a frame having a back plate and a side wall protruding fromeach of multiple side edges of the back plate. The seat belt retractoralso includes a spool supported by the frame and configured to rotateand wind a seat belt, a motor configured to rotate the spool, and anelectronic control unit configured to drive and control the motor. Theelectronic control unit is mounted between the side walls of the frameand the back plate is disposed in an inner space of a vehicle bodymember and faces a vehicle interior direction.

Another embodiment of the disclosure relates to a seat belt retractorincluding a frame having a back plate and a side wall protruding fromeach of multiple side edges of the back plate. The seat belt retractoralso includes a spool supported by the frame and configured to rotateand wind a seat belt, a motor configured to rotate the spool, and anelectronic control unit configured to drive and control the motor. Themotor is mounted between the side walls and the electronic control unitis fixed to the motor. The back plate is disposed in an inner space of avehicle body member and faces a vehicle interior direction.

BRIEF DESCRIPTION OF THE DRAWINGS

The features, aspects, and advantages of the present disclosure willbecome apparent from the following description, appended claims, and theaccompanying exemplary embodiments shown in the drawings, which arebriefly described below.

FIG. 1 is a schematic view illustrating a seat belt retractor accordingto an exemplary embodiment.

FIG. 2 is a schematic view illustrating a seat belt retractor accordingto another exemplary embodiment.

FIG. 3 is a schematic view illustrating a seat belt retractor accordingto another exemplary embodiment.

FIG. 4 is a schematic view illustrating a seat belt retractor accordingto another exemplary embodiment.

FIG. 5 is a schematic view illustrating a seat belt retractor accordingto another exemplary embodiment.

FIG. 6 is a schematic view illustrating a seat belt retractor accordingto another exemplary embodiment.

FIG. 7 is a schematic view illustrating a seat belt apparatus accordingto an exemplary embodiment.

FIG. 8 is a schematic view illustrating a seat belt retractor used inthe seat belt apparatus illustrated in FIG. 7 according to an exemplaryembodiment.

DETAILED DESCRIPTION

According to various exemplary embodiments, a seat belt retractor maysuppress noise caused by a motor and an electronic control unit fromaffecting other electronic parts in the vehicle even when the motor andthe electronic control unit are integrally provided in a seat beltretractor. The seat belt retractor may also be more compact than aconventional retractor to improve ease of installation, removal, andmaintenance.

FIG. 7 is a schematic view illustrating a seat belt apparatus accordingto an exemplary embodiment and FIG. 8 is a schematic view illustrating aseat belt retractor used in the seat belt apparatus.

As illustrated in FIGS. 7 and 8, a seat belt apparatus 1 may be athree-point type seat belt apparatus and includes a seat belt 3, a beltanchor 3 a, a seat belt retractor 6, a guide anchor 7, a tongue 8, and abuckle 9. The belt anchor 3 a at a tip end of the seat belt 3 is fixedto a vehicle body floor or a vehicle seat 2. The seat belt retractor 6is fixed to a vehicle body and retracts the seat belt 3 by rotating aspool 5 with an electric motor 4. The guide anchor 7 guides the seatbelt 3 as it is withdrawn from the seat belt retractor 6 toward ashoulder of the occupant. The tongue 8 is slidably supported by the seatbelt 3. The buckle 9 is fixed to the vehicle body floor or the vehicleseat 2 and the tongue 8 is inserted and engaged or removed anddisengaged.

The seat belt retractor 6 includes a C-shaped frame 10 having a backplate 10 a, a left side wall 10 b, and a right side wall 10 c. The leftand right sidewalls 10 b, 10 c protrude from the left and right sides ofthe back plate 10 a. The seat belt retractor 6 receives the seat belt 3and the spool 5 is supported by the frame 10 and rotates to retract theseat belt 3. The seat belt retractor 6 includes a spring device 11 thatis supported by the frame 10 and biases the spool 5 in a seatbelt-retracting direction. The motor 4 drives or rotates the spool 5 andis supported by the frame 10. A power transmission mechanism 12 issupported by the frame 10, transmits power from the motor 4 to the spool5, and converts the speed of the motor 4. A circuit board 14 issupported by a cover 13 on a side wall 10 b at a left side of the frame10 and includes a printed circuit 14 a for driving and/or controllingthe motor 4. The printed circuit 14 a of the circuit board 14 iselectrically connected to the motor 4 and a power source.

A vehicle sensor (e.g., a deceleration sensing mechanism) may beactivated when a predetermined deceleration threshold is reached orsurpassed by the motor vehicle (e.g., a collision, hard braking, etc.).A webbing sensor may be activated when the worn seat belt 3 is rapidlywithdrawn at a speed higher than a typical withdrawal speed of the seatbelt 3. A locking mechanism for locking the rotation of the spool 5 in aseat belt-withdrawing direction may be provided in the right side wall10 c of the frame 10 and may be activated by the activation of any oneof the vehicle sensor or the webbing sensor.

Seat belt retractors are generally disposed in a narrow space inside avehicle, for example a space inside a center pillar or the like. Avehicle body may include an opening (e.g., in the center pillar, etc.)for installing or removing the seat belt retractor.

According to an exemplary embodiment, the circuit board 14 may beattached to the seat belt retractor 6. The motor 4 and circuit board 14may generate noise when the circuit board 14 is active and the motor 4is actuated. It is preferred that other electronic parts of the motorvehicle not be affected by the noise generated from the motor 4 and thecircuit board 14.

When the circuit board 14 is attached to the seat belt retractor 6, thestrength of the frame 10 should be sufficient to mount and protect thecircuit board 14. Strengthening the frame 10 typically increases thewall thickness of the frame 10 or the structural size of the frame mayincrease or include more parts, increasing the size of the seat beltretractor 6. The size of the seat belt retractor 6 may also increase toaccommodate the size of the circuit board 14. A larger sized seat beltretractor 6 may be more difficult to assemble or service in the limitednarrow space inside the motor vehicle (e.g., the inner space of thecenter pillar).

According to various exemplary embodiments, the seat belt retractor maybe capable of suppressing noise so the noise does not other electronicparts, even when the electronic control unit is attached to the motor.Further, the seat belt retractor may be compact to improve assembly,installation, or servicing of the retractor or seat belt apparatus.

According to an exemplary embodiment, a seat belt retractor including aframe having a back plate and a side wall protruding from each ofmultiple side edges of the back plate. The seat belt retractor alsoincludes a spool supported by the frame and configured to rotate andwind a seat belt, a motor configured to rotate the spool, and anelectronic control unit configured to drive and control the motor. Theelectronic control unit is installed or mounted between the side wallsof the frame and the back plate is disposed in an inner space of avehicle body member and faces a vehicle interior direction.

According to an exemplary embodiment, the electronic control unit ismounted between side end edges of the side walls and the motor isdisposed below or above the side walls of the frame.

According to an exemplary embodiment, the electronic control unit ismounted between lower edges of the side walls and the motor is fixed toa lower surface of the electronic control unit.

According to an exemplary embodiment, the electronic control unit ismounted between upper edges of the side walls and the motor is fixed toan upper surface of the electronic control unit.

According to an exemplary embodiment, a seat belt apparatus includes theseat belt retractor for performing at least one of retracting andwithdrawing operations for a seat belt by rotating a spool with a motor.The seat belt apparatus also includes a tongue slidably supported by theseat belt and a buckle with which the tongue is disengaged or engaged.An occupant may be restrained by the seat belt when the tongue isengaged with the buckle.

According to another exemplary embodiment, a seat belt retractorincluding a frame having a back plate and a side wall protruding fromeach of multiple side edges of the back plate. The seat belt retractoralso includes a spool supported by the frame and configured to rotateand wind a seat belt, a motor configured to rotate the spool, and anelectronic control unit configured to drive and control the motor. Themotor is mounted between the side walls and the electronic control unitis fixed to the motor. The back plate is disposed in an inner space of avehicle body member and faces a vehicle interior direction.

According to another exemplary embodiment, the motor is mounted betweenlower edges of the side walls and the electronic control unit is fixedto a lower surface of the motor.

According to another exemplary embodiment, the motor is mounted betweenupper edges of the side walls and the electronic control unit is fixedto an upper surface of the motor.

According to various exemplary embodiments, noise can be shielded by avehicle body member (e.g., a center pillar) and the back plate of aframe even when the electronic control unit is activated at the sametime a motor is actuated because the electronic control unit is mountedat the side walls of a frame and is covered with a vehicle body member(e.g., a center pillar or the like) and a back plate of the frame.Therefore, the possibility that noise is leaked outside the inner spaceof the vehicle body member is reduced and the noise can be suppressedaffecting other electronic parts of the motor vehicle.

The electronic control unit can be used as a reinforcing member for theframe because the electronic control unit is attached to a surface ofthe back plate facing the vehicle interior at a position facing bothside walls of the frame (as compared with when the electronic controlunit is provided on one of the side walls). Thus the strength of theframe can be increased without increasing the wall thickness of theframe or complicating or enlarging the structural size of the frame.Even when the electronic control unit is attached to the seat beltretractor, the seat belt retractor can be lightweight and compact.Assembly and servicing of the seat belt retractor in the limited narrowspace inside the motor vehicle (e.g., an inner space of the centerpillar, etc.) may be easier.

The electronic control unit may be attached to the back plate at aposition facing both side walls of the frame allowing the electroniccontrol unit to function as a counter weight to suppress vibration ofthe seat belt retractor.

The electronic control unit may be provided at the same side (vehicleexterior direction side) as that of the motor in relation to the backplate of the frame allowing the electronic control unit to be placedcloser to the motor. Thus the seat belt retractor can be more compactand an electric connection between the electronic control unit and themotor can be simplified.

The electronic control unit may be disposed between the frame and themotor, the electronic control unit may be protected from an externalforce by the frame and the motor.

The motor and the electronic control unit may be attached to each otherallowing the electric connection between the electronic control unit andthe motor to be simplified, the length of the wiring to be reduced, andassembly of the seat belt retractor (including the motor and theelectronic control unit) to take less time. Because both of the motorand the electronic control unit are disposed below or above the sidewalls of the frame, dead spaces of the side walls can be moreeffectively utilized to mount the motor and the electronic control unit.

The electronic control unit and the motor may bee mounted at an upperpart of the side walls allowing the electronic control unit and motor tobe placed closer an upper side of the retractor frame for mounting to aposition of the vehicle body. Even when the electronic control unit isattached to the motor in the seat belt retractor, the weight of theelectronic control unit and the motor may be dispersed to the side wallsof the frame and to the upper side of the frame.

The electronic control unit may be surrounded by the back plate, sidewalls, and the upper part of the frame and so the electronic controlunit can be protected from the external force by the back plate, sidewalls, and upper part of the frame.

According to other exemplary embodiments, an inner space of a vehicleinterior may be less wastefully occupied by the seat belt retractor evenwhen the seat belt retractor includes the electronic control unitattached to the motor because the seat belt retractor may be compact andcapable of being assembled in a narrow space of the vehicle body (e.g.,an inner space of the center pillar). The restraining capability for anoccupant can be adjusted by a belt tension control for the seat beltwith the motor while maintaining occupant comfort.

FIG. 1 is a schematic view illustrating an exemplary embodiment of aseat belt retractor. In the description of the respective exemplaryembodiments below, the same reference numerals used in reference to thesame components as that of FIG. 1 and a detailed explanation for thecomponents is omitted.

As illustrated in FIG. 1, a seat belt retractor 6 of the first exampleincludes a metal C-shaped frame 10 and a spool 5 supported by the frame10 and rotating to wind a seat belt 3. The seat belt retractor 6includes an electric motor 4 for rotating the spool 5 in both abelt-retracting direction and a belt-withdrawing direction and agenerally flat plate-shaped electronic control unit (ECU) 16 for drivingand controlling the motor 4. The seat belt retractor 6 is configured toperform both retracting and withdrawing operations for the seat belt 3using a driving force of the motor 4.

The motor 4 is disposed at the same side of a back plate 10 a as thespool 5 and is below side walls 10 b and 10 c of the frame 10 (since theside wall 10 c is visually overlapped with the side wall 10 b, only thereference numeral is shown in brackets). The motor 4 is detachably fixedto at least one of the back plate 10 a, side wall 10 b, and side wall 10c so that a longitudinal direction of the motor 4 (e.g., an axialdirection of a rotation shaft of the motor 4) is parallel to an axialdirection of the spool 5.

The ECU 16 is mounted between side end edges 10 b 1 and 10 c 1 of theside walls 10 b and 10 c opposite a side of the back plate 10 a. The ECU16 is detachably attached to a lower portion of the side end edges 10 b1 and 10 c 1 that is situated nearest the motor 4. Therefore, a lengthof the wiring for an electric connection of the ECU 16 and the motor 4can be reduced and the ECU 16 and motor 4 may be more easilyelectrically connected. The motor 4 and the ECU 16 are attached to eachother or integrally formed in the seat belt retractor 6. Otherconstructions of the seat belt retractor 6 of may be substantially thesame as that of the exemplary embodiment illustrated in FIG. 8.

The constructed seat belt retractor 6 may be disposed at, for example,an inner space formed from a metal center pillar 17 (corresponding to avehicle body member), namely a side of a vehicle exterior of the centerpillar 17 so that the back plate 10 a faces a vehicle interior directionas illustrated in FIG. 1. Most parts of the seat belt retractor 6 towhich the ECU 16 is attached are covered with the center pillar 17. TheECU 16 is configured to face the vehicle exterior direction where theseat belt retractor 6 is attached to the vehicle body. Both of the motor4 and the ECU 16 are covered with the center pillar 17 and the backplate 10 a and little of the motor 4 or ECU 16 is directly exposed tothe vehicle interior. The seat belt retractor 6 may be removed orinstalled in the inner space of the center pillar 17 through an opening17 a.

Both the motor 4 and the ECU 16 are covered with the center pillar 17and the back plate 10 a and thus noise can be shielded by the centerpillar 17 and the back plate 10 a even when the noise is generated froman active ECU 16 and actuated motor 4. The amount of noise leaked out ofthe inner space of the center pillar 17 is reduced and can be suppressedfrom affecting other electronic parts of the motor vehicle.

The ECU 16 is mounted between the side end edges 10 b 1 and 10 c 1 ofthe respective side walls 10 b and 10 c of the frame 10. The ECU 16 canbe used as a reinforcing member for the frame 10 (in comparison withwhen the ECU 16 is attached on only one the side walls 10 b and 10 c).Therefore, the strength of the frame 10 can be increased withoutincreasing the wall thickness, size, or complexity of the frame 10. Evenwhen the ECU 16 is attached to the seat belt retractor 6, the seat beltretractor 6 can be lightweight and compact improving the ease ofassembly or service of the seat belt retractor 6 in the limited narrowspace inside the motor vehicle (e.g., an inner space of the centerpillar 17).

The ECU 16 is mounted between the side end edges 10 b 1 and 10 c 1 ofthe respective side walls 10 b and 10 c of the frame 10 and can functionas a counterweight to suppress vibration of the seat belt retractor 6.

The ECU 16 is installed at the same side of the back plate 10 a (vehicleexterior direction side) as the motor 4 and so the ECU 16 can be placedcloser to the motor 4. The seat belt retractor 6 can be more compact andthe electric connection between the ECU 16 and the motor 4 can besimplified. Other operation and advantages of the seat belt retractor 6may be substantially similar to those of the exemplary embodimentillustrated in FIG. 8.

FIG. 2 is a schematic view illustrating another exemplary embodiment ofthe seat belt retractor. Although the motor 4 is disposed below bothside walls 10 b and 10 c in FIG. 1, the motor 4 may be disposed aboveboth side walls 10 b and 10 c in the seat belt retractor 6 according toother exemplary embodiments. The motor 4 may be fixed to at least one ofthe back plate 10 a, the side wall 10 b, and the side wall 10 c. The ECU16 is detachably attached to an upper part of the frame 10 situatednearer the motor 4 between the side end edges 10 b 1 and 10 c 1. Themotor 4 is disposed at an upper part of the side walls 10 b and 10 c.Other construction, operation, and advantages of the seat belt retractormay be substantially similar to those of the exemplary embodimentillustrated in FIG. 1.

FIG. 3 is a schematic view illustrating another exemplary embodiment ofthe seat belt retractor. Although the ECU 16 is mounted between the sideend edges 10 b 1 and 10 c 1 of the respective both side walls 10 b and10 c in FIG. 1, according to other exemplary embodiments the ECU 16 maybe mounted between lower edges 10 b 2 and 10 c 2 of side walls 10 b and10 c. The motor 4 is fixed to a lower surface of the case of the ECU 16.The ECU 16 is disposed between the frame 10 and the motor 4 and the ECU16 can be protected from an external force by means of the frame 10 andthe motor 4.

The motor 4 and the ECU 16 are attached to each other or integrallyformed and so the electric connection between the ECU 16 and the motor 4may be further simplified reducing the length of the wiring betweenthem. The amount of time needed to assemble, install, or service themotor 4 and the ECU 16 can also be reduced. The motor 4 and the ECU areboth disposed below both side walls 10 b and 10 c of the frame 10 moreeffectively utilizing dead spaces of the side walls 10 b and 10 c. Otherconstruction, operation, and advantages of the seat belt retractor maybe substantially similar to those of the exemplary embodimentillustrated in FIG. 1.

FIG. 4 is a schematic view illustrating another exemplary embodiment ofthe seat belt retractor. Although the ECU 16 is mounted between thelower edges 10 b 2 and 10 c 2 of both side walls 10 b and 10 c of theframe 10 and the motor 4 is fixed to the lower surface of the case ofthe ECU 16 in the exemplary embodiment of FIG. 3, the motor 4 may bemounted between the lower edges 10 b 2 and 10 c 2 and the ECU 16 can befixed to a lower surface of a case of the motor 4 according to otherexemplary embodiments. Other construction, operation, and advantages ofthe seat belt retractor may be substantially similar to those of theexemplary embodiment illustrated in FIG. 3.

FIG. 5 is a schematic view illustrating another exemplary embodiment ofthe seat belt retractor. Although the ECU 16 is mounted between thelower edges 10 b 2 and 10 c 2 and the motor 4 is fixed to the lowersurface of the case of the ECU 16 in the exemplary embodiment of FIG. 3,the ECU 16 can be mounted between the upper edges 10 b 3 and 10 c 3 ofboth side walls 10 b and 10 c and the motor 4 can be fixed to an uppersurface of the case of the ECU 16 according to other exemplaryembodiments.

The ECU 16 and the motor 4 are provided at an upper portion 10 d of theframe 10 that is attached to the vehicle body and so the ECU 16 and themotor 4 can be placed closer to the position the retractor is attachedto the vehicle body. Even when the ECU 16 and the motor 4 are attachedto each other in the seat belt retractor 6 the weight of the ECU 16 andthe motor 4 may be dispersed to both side walls 10 b and 10 c and to theupper portion 10 d.

The ECU 16 is surrounded by the back plate 10 a, side walls 10 b and 10c, and the upper portion 10 d of the frame 10 allowing the ECU 16 to beprotected from an external force by the back plate 10 a, side walls 10 band 10 c, and the upper portion 10 d. Other construction, operation, andadvantages of the seat belt retractor may be substantially similar tothose of the exemplary embodiment illustrated in FIG. 3.

FIG. 6 is a schematic view illustrating another exemplary embodiment ofthe seat belt retractor. Although the ECU 16 is mounted between theupper edges 10 b 3 and 10 c 3 of the side walls 10 b and 10 c and themotor 4 is fixed to the upper surface of the case of the ECU 16 in theexemplary embodiment of FIG. 3, the motor 4 may be mounted between theupper edges 10 b 3 and 10 c 3 and the ECU 16 may be fixed to an uppersurface of the case of the motor 4 according to other exemplaryembodiments. Other construction, operation, and advantages of the seatbelt retractor may be substantially similar to those of the exemplaryembodiment illustrated in FIG. 5.

The seat belt retractor of the present disclosure is not limited to theabove-described exemplary embodiments. For example, the seat beltretractor can be configured to perform only the retracting operation forthe seat belt using a driving force of the motor or can be configured toperform only the withdrawing operation for the seat belt. The seat beltretractor may be configured to perform at least one of the retractingand withdrawing operations for the seat belt.

Each of the described respective seat belt retractors illustrated inFIGS. 1-8 can be used in a three-point type seat belt apparatus 1, asillustrated in FIG. 7 for example.

The seat belt retractor 6 may be compact and may be assembled into anarrow space such as the inner space of the center pillar. An innerspace of the vehicle interior of a motor vehicle may be less wastefullyoccupied by the seat belt retractor 6 even when the seat belt retractor6 includes the motor 4 and the ECU 16 is provided. The restrainingcapability for an occupant can be adjusted by a belt tension control forthe seat belt 3 with the motor while maintaining occupant comfort.

The seat belt retractor and seat belt apparatus can be used to performat least one of retracting and withdrawing operations for the seat beltby controlling rotation of a spool with a motor.

The priority application, Japanese Patent Application No. 2007-221360,filed Aug. 28, 2007 including the specification, drawings, claims andabstract, is incorporated herein by reference in its entirety.

It is important to note that the arrangements of the seat beltretractor, as shown, are illustrative only. Although only a fewembodiments of the present disclosure have been described in detail,those skilled in the art who review this disclosure will readilyappreciate that many modifications are possible (e.g., variations insizes, dimensions, structures, shapes and proportions of the variouselements, values of parameters, mounting arrangements, materials,colors, orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter recited herein. Manymodifications are possible without departing from the scope of theinvention unless specifically recited in the claims. Accordingly, allsuch modifications are intended to be included within the scope of thepresent disclosure as described herein. The order or sequence of anyprocess or method steps may be varied or re-sequenced according toalternative embodiments. Other substitutions, modifications, changes,and/or omissions may be made in the design, operating conditions andarrangement of the preferred and other exemplary embodiments withoutdeparting from the exemplary embodiments of the present disclosure asexpressed herein.

1. A seat belt retractor comprising: a frame, the frame comprising: aback plate, and a side wall protruding from each of multiple side edgesof the back plate; a spool supported by the frame and configured torotate and wind a seat belt; a motor configured to rotate the spool; andan electronic control unit configured to drive and control the motor,wherein the electronic control unit is fixed to the motor, and whereinthe electronic control unit and the motor are disposed above the sidewalls or below the side walls.
 2. The seat belt retractor according toclaim 1, wherein the electronic control unit is disposed below the loweredges of the side walls.
 3. The seat belt retractor according to claim2, wherein the electronic control unit is fixed to a lower surface ofthe motor.
 4. The seat belt retractor according to claim 1, wherein theelectronic control unit is disposed above the upper edges of the sidewalls.
 5. The seat belt retractor according to claim 4, wherein theelectronic control unit is fixed to an upper surface of the motor. 6.The seat belt retractor according to claim 4, wherein the electroniccontrol unit is surrounded by the back plate, the side walls, and anupper portion of the frame such that the electronic control unit isprotected from an external force.
 7. A seat belt apparatus comprising: aseat belt retractor including a frame having a back plate and a sidewall protruding from each of multiple side edges of the back plate;wherein the retractor further includes a spool supported by the frameand configured to rotate and wind a seat belt, a motor configured torotate the spool in order to perform at least one of retracting andwithdrawing operations for a seat belt, and an electronic control unitconfigured to drive and control the motor, wherein the electroniccontrol unit is fixed to the motor and wherein the electronic controlunit and the motor are disposed above the side walls or below the sidewalls; a tongue slidably supported by the seat belt; and a buckle withwhich the tongue is disengaged or engaged, wherein an occupant isrestrained by the seat belt when the tongue is engaged with the buckle.8. A seat belt retractor comprising: a frame, the frame comprising: aback plate, and a side wall protruding from each of multiple side edgesof the back plate; a spool supported by the frame and configured torotate and wind a seat belt; a motor configured to rotate the spool; andan electronic control unit configured to drive and control the motor,wherein the electronic control unit is fixed to the motor and whereinthe electronic control unit and the motor are disposed above the sidewalls or below the side walls.